1. Field of the Invention
The present invention relates to a browsing unit in a distributed hyper media system, and more particularly, to a browsing unit which allows efficient navigation.
2. Description of the Prior Art
Normally, a distributed hyper media system comprises a plurality of servers for distributed management of data comprising nodes and links on a network and a client computer for obtaining necessary data by accessing the servers on demand of a user. As the client, a unit which receives a request for obtaining data from a user, obtains a node from an appropriate server, and displays the content information of the node is referred to as a browsing unit.
Each of the nodes has a link to a node related thereto. With such a browsing unit, a user can obtain a related node by following the link. Related nodes can be obtained one after another by following links. This operation is referred to as navigation.
As a distributed hyper media system of this kind, the WWW (World Wide Web) is widely used. When access to the WWW is made, a browsing unit such as "Mosaic" or "Netscape" is used to obtain content information of a node. An example of a conventional browsing unit is disclosed in an article entitled "WebMap: a graphical hypertext navigation tool" by Peter Domel, published in the Computer Networks and ISDN Systems, on pages 85-97, issued in 1995 by Elsevier Science, B. V.
FIG. 20 is a block diagram for describing a conventional browsing unit used for the WWW. This conventional browsing unit 800 comprises an input means 801 for receiving an input from a user such as a navigation operation, a content information output means 802 for outputting content information of a node obtained by a server, an information obtaining means 803 for obtaining content information of a node from a server, and a historical information storing means 810 for managing information about obtaining of a node in the past.
In the operation of the browsing unit, data requested from the input means 801 is obtained from a server computer by the information obtaining means 803. The content information output means 802 displays the content information of the node obtained by the information obtaining means 803. At the same time, the information obtaining means 803 records, as historical information, an identifier representing the location of the data the obtaining of which was requested and the date and time of the last access to the data.
However, since the conventional distributed hyper media system does not retain the overall structure of the nodes and links under distributed management, there is a problem that the browsing unit can not capture the macro structure comprising nodes and links on the distributed hyper media space. For example, though a user can tell a node linked directly to the node being viewed now, he (or she) can not tell a node linked to the node linked directly to the node being viewed now, and nor can he (or she) tell connected nodes from the macro viewpoint. Since a user can not see far ahead of the linked node, he (or she) is forced to conduct a wasteful operation to check the content information of the linked node by actually following links one by one on the browser.
Further, though the conventional browsing unit can tell whether the node is one which it accessed in the past, it can not tell whether the node is frequently used or seldom used.
In addition, since the historical information is not displayed graphically, it is difficult to tell how frequently a node following a certain link was accessed in the past. Therefore, though navigation is made in search of new information, it tends to be inefficient navigation in which, for example, a node frequently used is accessed many times.